1. Technical Field
The present invention relates to a method for manufacturing an elongated windshield wiper blade to be placed in abutment with a windshield to be wiped, the method comprising the steps of                providing a tandem wiper blade made in one piece of an elastomeric material, which is composed of two wiper blades integrally joined together; and        subsequently cutting the tandem wiper blade so as to separate the two wiper blades each having a wiping head facing away from a windshield to be wiped and a wiping lip to be placed in abutment with a windshield to be wiped.        
2. Related Art
Such a method is generally know, for example from European patent publication no. 0 657 331 (Fukoku). Use is made of a tandem wiper blade formed by a strip of starting material of rubber, wherein the strip of starting material consists of two wiper blades whose respective wiping edges are directed towards each other so as to form a common lip portion. A surface coating of nylon or graphite, for example, is applied to the tandem wiper blade, wherein rotary knives are used to separate the wiper blades. As small notches are formed by the rotary knives inside the common lip portion prior to applying the surface coating, wiping edges of the wiping lips of the wiper blades will not be covered with the surface coating, so that wiping properties thereof will not be deteriorated. In addition thereto, sharp edges of the rotary knives will not be abraded by the surface coating.
A disadvantage of the method known from the European patent publication no. 0 657 331 is that the form of the common lip portion and thereof also the forms of the wiping lips of the wiper blades forming the common lip portion cannot be accurately controlled. In practice this has led to a deformation of the wiping lips of the wiper blades resulting in inferior wiping properties thereof.